This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-242895, filed Aug. 10, 2000, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a coupling for fluid pipes, and more specifically, to a pipe coupling suitable for use with a vessel containing a chemical agent or the like that is used in the field of semiconductor manufacture, for example.
2. Description of the Related Art
Pipe couplings that are composed of a plug and a socket each are used in various chemical lines and ultrapure water lines in the fields of the semiconductor industry, bio-industry, and chemical-medical industry.
With the development of highly integrated semiconductor wafers in semiconductor manufacturing processes, which is involved in the rapid progress of the LSI or super LSI technology, in particular, the pipe couplings of this type are used in lines for various liquids, such as chemicals, and various treatment gases.
Normally, chemicals are received in vessels, which are utilized for the storage and transportation of the chemicals. In using a chemical agent in a vessel, the chemical agent is fed to the supply side in a manner such that a socket paired with a plug on the vessel is connected to and disconnected from the plug. Various vessels and pipe couplings used therein are proposed in Jpn. Pat. Publication No. 2761354 and Jpn. Pat. Appln. KOKAI Publication No. 11-193894.
In the pipe coupling described in Jpn. Pat. Publication No. 2761354, the distal end portion of a valve projects by a large amount from an opening in the distal end portion of a cylindrical main socket body, and a seal member seals a space between the socket and a plug on the outer peripheral surface of the plug.
In the pipe coupling described in Jpn. Pat. Appln. KOKAI Publication No. 11-193894, on the other hand, the distal ends of valves provided on a socket and a plug project from openings in a cylindrical main socket body and a plug body, and a seal member seals a space between the socket and a plug on the outer peripheral surface of the plug.
In both these pipe couplings, however, the distal ends of the valves project from the openings when the socket and the plug are connected, so that the outer peripheral surface of the plug must be sealed by means of an O-ring before the valves are opened. Thus, a space is formed between the opening of the socket and the distal end of the plug. Possibly, therefore, air may get into this space, and a fluid may drip out when the socket and the plug are separated from each other.
In a pipe coupling shown in FIG. 11, an O-ring 3 is provided on the end face of a socket 1 or a plug 2 without making the distal end of the valve project from an opening. When the socket 1 and the plug 2 are connected to each other, in this case, the O-ring 3 on the socket contacts the end face of the plug along a circular line. FIG. 11 shows a normal state that involves no problem. If bending force acts on the socket 1 and the plug 2, as shown in FIG. 12, however, there is no room for the O-ring 3 to collapse. Thus, the sealing properties become so poor that fluid leakage occurs.
If a spring and other fluid-contacted parts in a pipe coupling are not chemical-resistant, metal is eluted into a fluid, and particles are produced in a semiconductor manufacturing process or the like. These situations must be securely avoided for the semiconductor manufacturing process, in particular.
Further, fluid dripping that is caused as the pipe coupling is disconnected may cause a chemical agent or the like to flow out during the storage or transportation of the vessel, thereby endangering the operation. It is necessary, therefore, that a highly dangerous chemical agent should not leak from the vessel during filling operation.
Furthermore, it is essential securely to prevent wrong connect between a socket and a plug.
The present invention has been contrived in consideration of these circumstances, and its object is to provide a pipe coupling in which inflow of air can be reduced to a very low level when a socket and a plug are connected to each other and a fluid can be prevented from dripping out when the two members are separated from each other.
Another object of the invention is to provide a pipe coupling of which members that touch a fluid have chemical-resistance properties such that production of particles can be reduced.
Still another object of the invention is to provide a pipe coupling capable of securely preventing a fluid from flowing out even in case it drips.
An additional object of the invention is to provide a pipe coupling capable of preventing wrong connection between a socket and a plug.
In order to achieve the above objects, according to the present invention, there is provided a coupling for fluid pipes, comprising a plug having an outer peripheral groove; a socket capable of being connected to the plug, the socket including a socket body, a sleeve slidably fitted on the outer peripheral surface of the socket body and urged toward the distal end thereof, and a plurality of locking members provided on the socket body and capable of being engaged with and disengaged from the outer peripheral groove by means of the sleeve; a pair of end faces provided individually on the plug and the socket and adapted to abut against each other when the plug and the socket are joined; and a shaped packing provided on one of the coupling end faces and adapted to prevent admission of external air when the coupling end faces abut against each other and to prevent the fluid from leaking out when the coupling end faces are separated from each other.
According to this pipe coupling, inflow of air can be reduced to a very low level when the socket and the plug are connected to each other, and the fluid can be prevented from dripping out when the two members are separated from each other. If the pipe coupling is used in a semiconductor manufacturing process, for example, it can prevent the fluid from dripping out and securely prevent fluid leakage during filling operation for filling a harmful chemical agent into a vessel or the like.
Preferably, the shaped packing includes a body having a circular cross section and at least two ring-shaped lips protruding from one side of the body. If bending force acts on the socket and the plug, in this case, one of the lips of the packing can maintain the sealing function, so that leakage can be prevented with improved reliability.
Preferably, the sleeve has, on the rear end side thereof, display portions for preventing wrong connection with the plug. In this case, correct positions can be easily recognized when the sleeve of the socket is connected downward to the plug, so that the connection between the sleeve and the plug is easy. In order to prevent wrong connection, the sleeve or the plug has a projection projecting in the radial direction, and the other of the elements has an axial groove capable of receiving the projection.
In the case where the socket is provided with a grip portion axially extending from the rear end side of the socket body, the grip portion can be formed into an easy-to-grip shape. Therefore, the sleeve can be prevented from being unexpectedly touched as the socket is connected. Thus, wrong connection between the socket and the plug can be prevented, and the efficiency of connection and disconnection of the pipe coupling can be improved.
In the pipe coupling, the plug may be fixed in a cup-shaped plug holder which is capable of being attached to a vessel containing the fluid. The plug holder may includes a thread portion capable of being attached to the vessel and an opening for receiving the socket capable of being fitted with the plug, and a cap may be attached to the opening. Preferably, the cap includes an fixing portion capable of being fixed to the plug holder and a ring-shaped seal portion capable of being engaged with the inner peripheral surface of the opening.
In this case, the plug having its internal valve closed can be fixed in the plug holder, and the opening of the plug holder can be closed by means of the cap. If fluid dripping happens, therefore, the fluid can be prevented from flowing out of the pipe coupling, so that the pipe coupling can be used very safely.
If all of the members capable of touching the fluid are formed of a chemical-resistant material, the pipe coupling can be suitably used in a vessel containing a chemical agent or the like that is used in the field of semiconductor manufacture, for example.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.